Dérivés Alléniques du Phosphore. Influence de l'État de Coordination du Phosphore et de la Nature des Radicaux Liés au Phosphore sur les Signes de J(P?H)

The signs of the phosphorus-proton coupling constants in various allenic organophosphorus compounds have been determined by either analysis of the AB₂X spectra or double resonance. Probable absolute signs have been obtained by taking ³J(P? H) as positive. In allenic phosphine oxides, the following signs are obtained: ²J(P? H) +ve, ³J(P? H) +ve, ⁴J(P? H) ?ve, ⁵J(P? H) +ve and the ⁴J(P? H) coupling constant varies mostly with the inductive effect of the substituents bound to the phosphorus atom. In allenic phosphines, these sings are: ²J(P? H) +ve, ³J(P? H) +ve, ⁴J(P? H) ?ve and +ve and the ⁴J(P? H) coupling constant varies with both the inductive and resonance effects to the substituents. This coupling constant is negative except when the phosphorus atom is bound to groups which are electron-donating by resonance effects. These results are discussed in relation to the pπ? dπ bonding in phosphine.     

Étude théorique de l'oxime de l'acroléine

Résumé La méthode semi-empirique de Pariser-Parr-Pople est appliquée à l'étude des quatre isomères géométriques de l'oxime de l'acroléine, en utilisant les paramètres empiriques déterminés précédemment pour les oximes de la p-benzoquinone. L'analyse théorique des énergies totales permet de penser sans ambiguité que seule la forme -trans peut exister. Dans ces conditions, le spectre électronique calculé est en très bon accord avec les résultats expérimentaux.

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The Pariser-Parr-Pople's method is applied to the study of the four -geometric conforme of the oxime derived from acrolein, using empirical parameters precedently defined for the study of p- benzoquinone oximes. The theoretical analysis of total energies allow the conclusion that alone the -trans form may exist. In these conditions, the computed electronic spectrum is in good agreement with experimental data.

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Zusammenfassung Mit der PPP-Methode wurden die vier geometrischen Isomeren des Oxims des Acrolein behandelt. Dabei wurden die empirischen Parameter benutzt, die schon bei der Untersuchung des Oxims des p-Benzochinons verwandt wurden. Es ergibt sich, daß nur die -trans Form existiert und für diesen Fall auch das berechnete Elektronenspektrum mit den experimentellen Werten gut übereinstimmt.

     

Reactivity of 4-halogeno 1-vinyl naphthalenes in cationic polymerization

Improved methods for the synthesis of 4-halogeno 1-vinylnaphthalenes are proposed. Reactivity ratios are determined for the following systems: 4-fluoro-1-vinyl naphthalene-styrene, 4-chloro-1-vinyl naphthalene-styrene, and 4-bromo-1-vinyl naphthalene-styrene. The determinations are performed at various specific temperatures and the relative activation parameters are obtained. It appears that the reactivity of 1-vinyl naphthalene is drastically decreased when substituted by a halogen. In the case of 1-vinyl naphthalene the selection is enthalpically controlled.     

Etude comparative des proprietes magnetiques des oxydes lamellaires ACrO2 (A = Li,Na, K)—I: Etude par effet Mössbauer de LiCrO2 dope par le fer

A Mössbauer study of the dimensionality of magnetic interactions in the layer oxide LiCr_0.99Fe_0.01O₂ shows a 2-D behaviour.     

The electronic structure of sulphur chloride penta-fluoride

The electronic structure of SCIF₅ is computed within the framework of the CNDO/2 approximation on the basis of Kewley's microwave geometrical data and is compared with our previous results on SF₆. The charge distribution and the value of the dipole moment are discussed as a function of the F-S-F_ax angle and an inversion of the net charge on Cl is observed when passing through the 95° value for (F-S-F_ax) angle.